I'm not sure what the issue is. Perhaps its just lag keeping the NPC from showing up. It's not uncommon in areas such as uldah. Just in case you didn't know, you can go into your journal and click on the quest name. There you'll see a review of what you've done so far in the quest and there's a small "map" button. Click on that and it'll show you the location of where/who you need to go or talk to. If its a general location of something you need to kill, it'll be a big yellow circle. If its an NPC that you have to talk to, it'll show up a a small white circle with an "!" in the middle of it. If you ever have a question of where you need to go, just check the map and it'll point you in the right direction.
Just in the small chance you haven't seen this already. Here's a guide to the quest "Culture Shock" found on this website. It's not exactly detailed, but it'll get the job done.